The ink-jet recording method is a recording method in which a droplet of ink liquid composed of a solvent such as water and a colorant dissolved or dispersed in the solvent is jetted and adhered on a recording element. The ink-jet recording has an advantage that the recording can be performed silently and that various kinds of recording element can be used since the recording element is not contacted with any device.
However, when plain paper such as copy paper or reporting paper other than paper for ink-jet recording is used as the recording element, such problems tend to occur that the shape of dot is become uneven, so-called feathering, and that the colors different each other are mixed near the boundary thereof, so-called bleeding. As a result, problems are raised such as considerable degradation in the quality of the character or picture, lowering in the image density and easy wash away of the image by water. It is the present condition, therefore, that the paper exclusive for use of ink-jet recording is reqired.
A method for solving the above-mentioned problems has been proposed in Japanese Patent Publication Open for Public Inspection (JP O.P.I.) No. 4-372670, in which an ink containing a water-soluble dye and a pyrrolydone compound are used and the difference of pH value of the ink and that of the recording element is made 2 or more. This method has a problem that the recording element must be selected so as to fit with the ink. Use of an ink containing a specified polyol has been proposed in JP O.P.I. Nos. 6-172692, 4-211474, 4-211475 and 4-211476. When such the ink is used, the water resistivity of image cannot be apparently improved, even though the feathering and bleeding on palain paper are improved. Moreover, JP O.P.I. No. 4-332777 proposes an ink containing a polyalkyleneamine. Such the ink has a problem that the stability of ink is degraded even though the water resistivity is improved. JP O.P.I. No. 63-299970 proposes an ink-jet recording method in which an ink containing a dye having an acidic group is adhered to a recording element after a colorless or slightly colored liquid containing a poly-valent metal salt is adhered. Although the water resistivity can be raised by this ink-jet recording method, the improving effect on the bleeding at the boundary between different colors is insufficient since the image is formed by precipitation of the dye itself, and unevenness of density of image tends to be caused by uneven precipitation of the dye.
It has been found by investigation by the inventors that, in an ink-jet recording method using an ink containing a colorant and a liquid composition containing an anionic metal oxide colloid, the feathering and bleeding are considerably improved and the water resistivity of image is also considerably improved by adjusting the viscosity of the ink, the liquid composition and a mixture thereof at a specified value even when plain paper is used.